Microsphere-based immunoassays (MIAs) are becoming increasingly popular for laboratory diagnosis of many diseases (Earley et al., Cytometry 50:239-242, 2002; Kellar et al., Cytometry 45:27-36, 2001). The technology involves the detection and analysis of a reaction (such as an antibody or other ligand) attached to microspheres or beads. The detecting instrument is a simplified flow cytometer, and lasers simultaneously identify the microsphere sets and measure the fluorescence associated with the reaction. The speed at which these tests can be performed and the ability to multiplex make this methodology particularly useful.
Limited methods exist for rapid identification of antigen-specific antibodies in animal species for which commercial secondary antibody conjugates and/or antisera are unavailable. The available assays are often of a complex nature, involving the use of live pathogens. Antisera (such as goat anti-alligator IgM) can be used to coat an ELISA plate or couple to a microsphere, followed by addition of serum, antigen and then antigen-specific conjugate. However antisera are available for a limited number of species, and the availability of species-specific secondary antibody is even more limited. This makes surveillance for antigen-specific antibodies in some species, such as wild avian species or zoo animals, cumbersome. A need remains to develop a rapid and safe assay for detection of antigen-specific antibodies that can be used for any species.